Fertilizer manufacture



Patented Apr. 7, 1942 UNITED STATE PATENT o mnrmzua monotone Frank G.Keenen, Swarthmore, Pa,- assic'nor to Y E. I. du Pont de Nemours '&Company, Wilmington, nel 'acorporation of No Drawing.

This" invention relates-to fertilizers and more particularly to'theproduction of improved nitro-. gen-carrying fertilizermaterials.

It is well known that nitrogen is one of the elements required forsatisfactory plant growth and that the presence of nitrogen is,therefore,

necessary in a complete. fertilizer mixture.

Application February 17, 1940, Seth-1N0. 319,464 v 7 It is commonpractice in the fertilizer industry to treat acidic fertilizermaterials, especially those comprising largely mono-calcium phosphate,such as superphosphate or triple, superphosphate, with free ammonia toimproveftheir physical condition and to 'fix the otherwise nonusableammonia as an ammonium salt of the acid vpresent. The free ammoniaheretofore utilized" has been'employed in the form of gaseous ammonia,anhydrous ammonia, and various aqueous solutions containing free ammoniaalone or in conjunction with other nitrogen compounds such as urea,ammonium salts of inorganic acids, and

- inorganicv nitrates.

This practice has the disadvantage; however, that absorption of the freeammonia so added has resulted insubstantial increase intempera bygrowing vegetation.

It is any object of this invention to provide a new and improved processfor the ammoniation of acidic fertilizer materials in such a wayas toavoid the heat disadvantages of the' prior art.

It is an additional object of the present invention to provide a processfor the preparation of fertilizer materials containing nitrogencompounds not readily-soluble in water and-in a form ous conversion ofthe nitrogen in mixtures of acidic phosphates and urea to relativelyinsoluble forms has not heretofore been suggested.-

- The terms urea or a urea, 'as used herein,

refer to urea as such or derivatives of urea andcompounds which, incontact with acidic fertilizer materials, are converted tou'reaysuch ascalcium cyanamide:

The hexamethylene tetramine may, according to this invention, be addedalone, before, during or of r addition of other materials'in preparing aferti izer. Similarly, the hexamethylenetetramine, being a crystalline,water-soluble compound containing 40% nitrogen, may be easily added toacidic fertilizerv materialseontaining urea, or it a may be first mixedwith-the desired quantities of urea and thereafter added to acidicfertilizer'materials, orin*either of the above two cases, it may beadded to or substituted for ingredients of ammoniating\solutions,generally, such, for example, as the ammoniating or nitrifyingsolutions-describediuYU. S; Patent 1,894,136, whichgcontain: Again,

both inorganic and organic ammonia. proceeding according to thisinventionyhexamethylenetetramine may be'added to a phosphaticmaterialinithevpresence of urea, either before, after, or during addition ofotherrmatesuch that thenitrogen thereof becomes available toplantsgradually and over a relatively extended period of time. v g

Other objectsandadvantages of this invention 7 will be apparent from thefollowingspeciflcation in which its preferred details and embodimentsare described.

According to this'invention, hexamethylene tetramine is utilized asanon-exothermic source of ammonia for neutralizing the excess acidity ofand to condition mixtures of acidic fertilizer materials and urea and atthe same time to convert a substantial portion of the nitrogen compoundspresent to a relatively water-insoluble form. The possibility ofammoniating an acidic fertilizer mixture without a substantialtemperature rise has not existed with the nitrifying agents hererials,such, for example, as potash salts, including potassium sulfate,chloride, and nitrate; ammonium salts such as ammonium chloride,nitrate, sulfate, carbamate, mono-- and di-ammonium phosphates, or thelike; and then the product obtained may be further ammoniated by use ofcommercial aqua or anhydrous ammonia. Or, alternatively, the mixture ofurea and phosphatio material may be flrstammoniated, somewhat at least,by 'use of ammonia as above described and thereafter hexamethylenetetramine addedto the ammoniated product; or the hexamethylene tetraminemay be added during such" ammoniation with ammonia or likenitrogen-containing'material while, atthe same time, after or before,other materials such as above described may be added as are desired toobtain a finished fertilizer-t 7 As .a further feature of the presentinvention,

hexamethylene tetramine may be applied to acidic fertilizer materials inthe form of an aqueous solution which may or may notcontain free ammoniain addition tothat released by hexa- .methylene tetramine.

I Upon addition of these solutions to acidic, fertilizer materialscontaining urea or urea-forming substances such as calcium cyanamidthere is produced a nitrogenous fertilizer containing water-soluble, aswell as a substantial amount of relatively waterdnsoluble organicnitrogen.

in addition of hexamethylene mime to acidic fertilizer materials, I havefound that the hydrogen ion concentration or pH of the fertilizer toforedisclosed and, furthermore, the simultanematerials should fall within apH of 2 to 5 with F-FICEi I pH region between 3.5 and 4.5.

Within these ranges the hexamethylene tetra- I DE'ranges the orurea-forming present converted'to relativelyzwater-insolu ble compounds.There should. preferably, heap varied from about 3 to about lo'miole'sof per moleoi' hexamethylene tetramine.-- T

The following examples will illustrate the tree-1.

proximately 6 moles of moleof hexs-imethylene tetramine, althoughthis'r'atio may methylene tetramine with acidic fertilizer mate.-

as. of this invention, although the invention is not limited to theexamples. mm

ter insoluble nitrogen; w V I. "Various changes may be tionshereinbeforedescribed, aswell as-lin the 'method for preparing and emb yin t e li2,270,200 p complete fertiliser of desirable physical char'soeteristics, containing water-soluble as well as wawithout departing fromthe invention or sacrifice in! snlof the advantages thereof.

(Y 1. s procee'siof anemia some meme. materials which'comprisesincorporating hexarialsin the presence of urea.

2 '.,.A process ofammoniating fertiliser materi- 'alswhichcomprisesincorporating hexamcthylene tetrarnine with superphosphatein thepresence of w h: 1m one-1.9m. of win. I

super-phosphate PsOs) and 2139012! of lures. there was slowly mix'ed..inavconventioual mixing drumqlOO. pounds of hexamethylenetet- The processofammoniating acidic fertiliser @materials which comprises incorporatinghexamethylenetetramine lwithdan acidic fertiliser resulteda fertiliserbase of satise factory physical appearance containing; 16%

1 nitrogen: The base-canbe-used for ad-* potash saltsand the like. "T

mixture -with other 2 fertilizer;

is =12: t

V amnisde en ed -in Example 1, there was-added,

. soluble nitrogenawith 18% Althoughin in a mixingjdrum, 148 pounds ofan ammoniating terial having a ion concentration t in the range of pH=2topH=5.-

, m,-;B% water insoluble and 2% water-soluble.

solutloncontaining43% urea, 30% ammonia, and

21% water. .Aiter ammoniation there was' added. in the mixing drum,221poundsnof-solid 1,45. A process 4. Apromss of ammoniating fertiliser.materiwhich=comprises incorporating hexamethylene I tetramine withasuperphosphatein the presence of'furea. the; phosphate-having thehydrogen ion concentrationowithinithe range-"of pH=2 to PH'=5 VIV: L

. acidic fertilizer material intlie presence'of urea.

hexamethylene tetramine. The -product:.result-' ing. contained 1.25%insoluble nitrogen and 2.50%

out example the hexa'methylene tetramine was added after ammoniationhynise of g 6'. A process for the production of'a fertilisercontainingrelatively water insoluble organic ni trogen which comprisesincorporating an aqueous solution of hexamethylene tetramine with anacidic-fertilizer material lnthe' presencer f u an ammoniatingsolutionAt should be understood that this invention maybe practicedbythe'som mineperlo mol'esofurea. i

dition "of the r hexamethylene "tetramine before the. procedure of:

or together withtheiammoniatin'g solution. I 1

was mixed with 900.pounds:of commercial superphosphate 8% pounds'hexamethylenetetramine,

inter-mixture of these materials, therewas to the resulting product 58parts'jby wei'ghtof a I solution containing 43% urea,'30% ammonia, and27% water. :"Ihe. resulting mixturewas a completefertilizer of desirablephysical characterislac-utilized.

;7.:A processor ammoniating acidic fertiliser materials-.-.;which"comprises incorporatlng hea'a Example {there i manner similar '7 ample3. there was; mixed i together 1: with V 900 epound's of {commercialisuperphosphate, 18%, pounds of hexamethylene tetramine,'145 poundscalcium cyanamide, 230 pounds ammonium sul Y fate..l00-'poundspotassiumfchloridedw pounds v limestone and 417 pounds ofsand. JIhesemate rials were thoroughly mixed-in-a conventional rangemethylene tetramine with acidic fertilizerlmaterialsin'the presenceorurea, the ratio of hexamethylene xtetramine. added falling within theof from'3 totabout-lo'moles or urea per mole of hexamethylenetetrarnine. a 1

materials with hexanrethylenetetramine." w 1 9. In a"proces's"forammonlatin'g superphosphate containingureaythe step which comprisesneutralizing the escess acidity of'such materials.withhexamethylenetetramine. i l0. 'In"a;prooess for ammonistingacidlcifflitilizer materialscontaining urea;- the step which comprisesneutralizing the {excess acidity of such materials with'hexamethylenetetramine. .the

acidic fertilizer material having'a' ion concentration in therange of1911 210 pH=' 11.; In a process forj'amm'oniating phate in tlie prescncef theFstep'F which fcomprise's neutralizing the excess acidity of suchmaterials with hexamethy'lnetetraminc; the m.- perphosphate having ahydrogen ion concentrae tion within the range of pH=2*to pH'=6.for"theiproduction of a fertililr containing 1relativelywater-insolubleorganic ni.

- trogen which comprisesincorporating an aqueous soiutionofhexamethylene tetramine witlran

